This invention relates to a process for preparing 1-carba(dethia)cephalosporin antibiotic compounds. In particular, it relates to a free radical process for converting a cephalosporin 1,1-dioxide to a 1-carba(dethia)cephalosporin.
The 1-carba(dethia)cephalosporins have been obtained by total synthesis, for example, Christensen et al., U.S. Pat. No. 4,226,866, describe the preparation of 3-substituted methyl 1-carbacephalosporins, while Evans et al., U.S. Pat. No. 4,665,171, describe an asymmetric total synthesis. The 1-oxa(dethia)cephalosporins and the cephalosporins themselves have undergone extensive investigation and numerous therapeutically-useful antibiotics of these types have been developed. The 1-carba(dethia)cephalosporins have not been readily available for like investigation. Accordingly, methods for the preparation of the 1-carbacephalosporins are much sought after, particularly, methods which are amenable to large-scale production.